Problem: Ishaan starts counting at 36, and he counts by threes. If 36 is the 1st number that Ishaan counts. what is the 11th number that he counts?
What is the first number that he counts? $36$ What is the second number that he counts? $\begin{align*}&36 + 3 \\ &= 39\end{align*}$ What is the third number that he counts? $\begin{align*}&36 + 3 + 3 \\ &= 36 + (2 \times 3) \\ &= 42\end{align*}$ What is the 11th number that he counts? $\begin{align*}&36 + (10\times3) \\ &= 36 + 30 \\ &= 66\end{align*}$